Cut-off back-pressure valve for steam-engines



(No Model.) 2 Sheets--Sheet 1.

' W. H. LAWRENCE. GUT-'OFF BACK PRESSURB'VALVE FOR STEAM ENGINES.

V No. 418,034. Patented Dec. 24, 1889.

I-"Tgl 2 Sheets-Sheet 2.

(No Model.) v

w. 1 1.' LAWRENCE. GUT-OEF'BAGK PRBSSURE VALVB FOR STEAM ENGINES. I

No. 418.034. Patented Dec. 24, 1889.

WITNE 5.555 INVENT E\ F UN TED- STATES PATENT Ostren,

XVILLIAM H. LAXVRENCE, OF NE\VBURYPORT, MASSACHUSETTS( C UT-OFF BACK-PRESSURE VALVE FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 418,034, dated December 24, 18:89.

Application filed July 3, 1889. Serial No. 3l6,449. (No model.)

To all whom it may c'me/067%;

Be it known that I, WILLIAM H. LAWRENOE, of Newburyport, in the county of Essex and State of Massachusetts, have invented a new and Improved Automatic Out-Off Back-Pressure Valve for Steam-Engines, of which the following is a specification.

In this invention a Valve is placed near the eXhaust-steam valve, wherehy the exhauststean or a portion of it may be conveyed to pipes for heating purposes. This valve is provided with means for adjust-ment, so that the stroke may be cut off at any point when sufficient exhauststeam has been taken for that purpose, at once changing the engine from non-condensing to condensing for the remainder of the stroke. The same valve also saves all steam that may leak past the exhaust-valve, such stean (which would otherwise be lost) being also conveyed away for heating purposes.

The nature of the device is fullydescribed below, and is illustrated in the accompanying drawings, in whch- Figure 1 is a side elevation of a sufficient portion of a steam-engine to embody the in- Vention. Fig. 2 is a plan View taken on line rr, Fig. 1. Fig. 3 is a longitudinal vertical sec- 4 tion.

Similar letters of reference indicate like parts.

A represents the cylinder; B and-B', the

pisten and pisten-rod; O, the pitman; C', the

crank; D D, the ordinary eXhaust steam Valves; D' D', the inlet-valves; E, the exhanst-port; E', the exhaust, and F F are pipes leading to a heating system or contrivance.

H H are my valves placed near the exhaust- Valves D, connected therewith by passages H' H', and connecting with the pipes F F by passages H" H", at the ends of which are spring-valves h h of any suitable description.

In order that the operation of the ValVes H relative to the movement of the valves D may be understood, I will describe the actuating mechanism, much of which is of course not new in this invention.

a is an eccentric on the shaft a', (on which is the crank C'.) b is the eccentric-rod, pivotally secured to the lever c, pivoted at c'. d is a rod pivotally secured at its ends to the lever c and disk or hub e, by which the exhaustwalves I) D andtheinlet-valvesD' D' are operated through the agency of the rods g g, all constructed as usual. I I are rods pivotally secured at i to the lever c, and slotted at I' I' to receive pins Z Z, extending from the cams L, which are eceentrically placed on the shafts K, on which are fixed the Valves H H, which are the principal subject of my invention. Arms m m connect the cams L L with the dash-pot. N is a lever turning on the pivot c', and connected by a rod N' with the U-shaped frame O, pivotally secured to said rod and carrying a small rod or bar O'. This rod O' passes loosely through the two spreading springs P P, which are united to or integral with a standard P" and are provided on their outer sides with notches or teeth P' P', adapted to be engaged by notches L' L' on the cams lL L.

The operation is as follows: Taking the de- Vice in the position shown in Figs. 1 and 3, the left valves (in Fig. 3) D H are closed and the right Valves D H are open. The stroke is almost finished. As the stroke proceeds to afinish, the rod I pulls the cam K, connected with the left valve H, Fig. 3, until its notch L' catohes on the notch P' and pulls away the right valve, Fig. 3, from the notch P' next it, with the result that the left valve is opened and the right valve is closed. The reverse occurs at the other end of the stroke. Meantime the ordinary exhaust-valves D D have been operated in the usual manner by the mechanisn above described. The mechanism Operating the valves H I-I is timed so as to open said'valves a little after the Valves D D are opened and close them at about the same time. By this system less water is required for condensing, also smaller air-pumps, where such are used.

By snitably setting the nechanism the valves I-I can be used to save all the eXhauststeam, if necessary, or all eXhanst-steam can be turned into the condenser, as desired.

Having th'us fully described my invention, what I claim, and desire to secure by Letters Patent, is-- 1. The combination, with the oylinder A, provided with the eXhaust-steam v'alves D and eXhaust-ports E E', of the automatic Valves H, connected with the valves D by passages H' H', and with the stean-pipes by passages H" H", all arranged and constructed to oper` IOO ate substantially as and for the purpose set and pins Z, slotted rods I, and lever c, said forth. eams acting on the valves H, substantially as 2. The combnaton, With the mechanism and for the purpose described." v for Operating the eXhaust-steam valves, of the WILLIAM H. LAVVRENCE. 3 level' N, rod N', frame O O', Spreading arms WVtneSses:

or springs P, provided With the notehes 01' EDWARD H. BARTLETT, teeth P' cams L, provided With the teeth L' PAUL A. SMITHSON. 

